1. Field
Exemplary embodiments relate to an apparatus and method for obtaining a high dynamic range (HDR) image, and more particularly, to an apparatus and method for obtaining an HDR image by controlling an exposure time.
2. Description of the Related Art
A dynamic range of an image refers to a luminance level of an image ranging from a light area to a dark area, which can be represented. The dynamic range is adjusted by changing pixel values which indicate lightness (such as luminance) of an image. A method of implementing a high dynamic range (HDR) recently in the limelight may be roughly classified into three types as described below.
First one is a technique for enhancing the dynamic range and quality of image data being output from an image sensor by using an algorithm in image signal processing. Representative techniques are gamma correction and retinex image enhancement.
Second one is a technique for improving a dynamic range by obtaining two or more images having different exposure amounts and synthesizing those images. The images may be obtained by taking two pictures at different shutter speeds. The images are then synthesized and corrected by using a proper image signal processing algorithm.
Third one is a technique for obtaining two image data by disposing pixels having different sensitivities in a single pixel in an image sensor. Pixel data generated from the pixels having different sensitivities during an identical exposure time shows the same effect as image data generated to have different exposure amounts. Image data generated by the two pixels are synthesized and corrected, thereby obtaining a high dynamic range image.